Network switches have been used to forward packets from one node to another node. Such network switch devices include a first network port for receiving packets from a first node, and a second network port for passing the packets to a second node.
Some existing network switch devices include an active component, such as a processor or a switch module, configured to pass packets from a network port to an instrument port in accordance with a design scheme. The instrument port allows the packets to be transmitted to an instrument, such as an intrusion prevention system (IPS), sniffer, network monitoring system, application monitoring system, intrusion detection system, forensic storage system, and application security system, etc., so that the packets being transmitted from one node to another node may be analyzed and examined. The active components in such network switch devices require power to operate.
Some existing network switch devices also include a relay (FIG. 1). In the event of a power failure, the switch module cannot be operated, and the relay is configured to bypass the switch module, and physically connect two network ports, so that packets from one network port may be directly passed onto the other network port without being transmitted to the instrument port for processing by the monitor tool (FIG. 2).
Applicants of the subject application determine that use of relays in network switches as the immediate or only solution for addressing power failure may not be desirable. This is because relays may not be reliable. Also, existing relays may not support high speed signal, such as 250 Mhz or higher. In addition, when relays are used, the nodes that are communicating through the network switch device may see a link down for a very short duration (e.g., range of msec). The problem of having the communicating nodes see a link down event is that, if either or both of the nodes participate in the Spanning Tree Protocol (or the Rapid Spanning Tree Protocol), then the link down event may trigger a Spanning Tree Protocol re-configuration, which is not desirable. The link down will in turn cause causes data/packet loss.
Furthermore, when relays are used, the network switch device may fail the cable length distance requirement. The cable length distance is the maximum allowable or preferred distance dmax that is between two active components (e.g., components that require power to run). For example, the distance between a transmitting node (which may be an example of an active component) and the network switch device's switch module (which may be another example of an active component) may be d1, and the distance between a receiving node and the network switch device's switch module may be d2. In such cases, as long as the switch module in the network switch device is working, d1 may be as long as dmax, and d2 may be as long as dmax. (e.g., d1 may equal to dmax, and d2 may equal to dmax) (FIG. 1). However, when the network switch device's active component is not operating (e.g., due to power failure to the active component), and when relays are used to directly couple the two communicating nodes, then the requirement becomes that d1+d2≦dmax (FIG. 2). In the above example, if d1 already has a length that is dmax (d1=dmax) and d2 already has a length that is dmax (d2=dmax), then d1+d2=2dmax, which would exceed the cable length distance requirement of d1+d2≦dmax.
For the foregoing reasons, applicants of the subject application determine that it would be desirable to provide improved network switch devices that do not use relay as the immediate or only solution for addressing power failure.